#include <fstream>
#include <iostream>
#include <string>

using namespace std;

int main() {
    ifstream in("in.txt", ios::in);
    if (!in) {
        cout << "error opening file in.txt" << endl;
        return 0;
    }

    char c;
    ofstream casar("casar.txt", ios::out);
    
    while (in.get(c)) {
        c += 3;
        casar << c;
    }

    in.close();
    casar.close();

    return 0;
}